Tourniquet systems are commonly used in limb surgery. Typical surgical tourniquet systems of the prior art include a tourniquet cuff which encircles the limb of a surgical patient and a tourniquet instrument which is releasably connected to an inflatable portion within the tourniquet cuff through a length of tubing, thereby establishing a gas-tight passageway between the cuff and the tourniquet instrument. The tourniquet instrument supplies pressurized gas to inflate and regulate the pressure in the tourniquet cuff above a minimum pressure required to stop arterial blood flow distal to the cuff, for a duration suitably long for the performance of a surgical procedure. Many types of surgical tourniquet systems have been described in the prior art, such as those described by McEwen in U.S. Pat. Nos. 4,469,099, 4,479,494, 5,439,477 and McEwen and Jameson in U.S. Pat. Nos. 5,556,415 and 5,855,589.
Tourniquet systems are increasingly used in pre-surgical settings to stop arterial blood flow and thereby reduce blood loss, morbidity and mortality. For example, specialized emergency and military tourniquets based on apparatus described by McEwen et al in U.S. Pat. No. 6,746,470 have been used in combat settings, field hospitals and in civilian pre-hospital settings. In comparison to earlier, non-pneumatic device of the prior art, the pneumatic tourniquet apparatus described by McEwen et al in U.S. Pat No. 6,746,470, reduces unnecessary injuries by reducing the pressure levels and pressure gradients required to stop arterial blood flow in limbs reliably and safely.
Typically, tourniquet cuffs of the prior art encircle a patient's limb at a desired location. Studies published in the surgical literature have shown that the safest tourniquet inflation pressure is the lowest pressure that will stop the flow of arterial blood past a specific tourniquet cuff applied to a specific patient for the duration of that patient's surgery. Such studies have shown that higher tourniquet inflation pressures are associated with higher risks of tourniquet-related injuries to the patient.
It has been also been shown in the published literature that higher pressure gradients are associated with higher probabilities of injuries. Pressure gradients are produced on limbs beneath tourniquet cuffs and extend across the width of the cuffs. Variables that affect pressure gradients produced on limbs by encircling pneumatic tourniquet cuffs include: cuff width; cuff design and materials; characteristics of any stiffening element or means within the cuff; shape and size of any inflatable region of the cuff; degree of match between the shape of the limb and shape of the encircling cuff; and the inflation pressure level employed to stop blood flow. Typically, tourniquet cuffs of the prior art have only been useful when a sufficient width of a patient's limb is available for the application of the tourniquet cuff so that it can encircle the limb and overlap upon itself. However, there are many situations in which there is a need to reliably and safely stop arterial blood flow and in which the use of prior-art tourniquet cuffs is not possible. For example, prior-art encircling tourniquet cuffs may not safely and reliably stop arterial blood flow in the limbs of short and obese patients. Other situations include certain traumatic injuries to the proximal portions of limbs that leave insufficient room for application of a prior-art tourniquet cuff, and situations in which traumatic injuries to limbs would extend beneath a prior-art tourniquet cuff if applied. In addition, for certain surgical procedures not involving limbs, there is a need for apparatus that can selectively stop arterial blood flow in order to facilitate surgery, to reduce surgical precision and time, to increase safety and to improve long-term surgical outcomes. Such procedures include surgery of the hip, surgery of the shoulder and abdominal surgery. For a variety of procedures performed on limbs, there is a need for apparatus which could safely and reliably stop blood flow in selected arteries, rather than stopping all blood flow in all vessels that would otherwise underlie an encircling prior-art tourniquet cuff. The present invention addresses these needs.